Anatomy of the Ureters Prof . Talib jawad

2020

definition:

ureters are a pair of narrow, thick-walled muscular tubes which conveey urine from the kidneys to the urinary bladder. They lie beneath the peritoneum, closely applied to the posterior abdominal wall in upper part, and to the lateral pelvic wall in the lower part.

Each ureter is about 25 cm long, of which the upper half lies in abdomen, and the lower half in pelvis. It measures about 3mm in diameter, but it is slightly constricted at three places: 1- at the pelvi-ureteral junction. 2- at the brim of the lesser pelvis. 3- at its passage through the bladder wall.

Course Ureter begins within the renal sinus, as a funnel-shaped dilatation, called the renal pelvis. Gradually it narrows till at the lower end of the kidney it becomes the ureter proper. The ureter passes downwards and slightly medially on the psoas major muscle, and enters the pelvis by crossing in front of the termination of the common iliac artery.

In the pelvis the ureter runs

downwards and laterally

following the anterior margin

of the greater sciatic notch.

Opposite the ischial spine it

turns forwards and medially to

enters the bladder wall

obliquely and open at the

lateral angle of its trigon.

Structure

The ureter is composed of three coats: fibrous, muscular, and mucous coats. The fibrous coat (tunica adventitia) is continuous at one end with the fibrous tunic of the kidney on the floor of the sinus; while at the other it is lost in the fibrous structure of the bladder. In the ureter proper the muscular fibers (tunica muscularis) are very distinct, and are arranged in three layers: an external longitudinal, a middle circular, and an internal, less distinct than the other two, but having a general longitudinal direction.

The mucous coat (tunica mucosa) is smooth, and presents a few longitudinal folds which become effaced by distension. It is continuous with the mucous membrane of the bladder below, while it is prolonged over the papillæ of the kidney above.

Relations (A) Abdominal part Anteriorly:

Right ureter

the duodenum, the terminal part of the ileum, the right colic and ileocolic vessels, the right ovarian vessels, and the root of the mesentery of the small intestine.

Left ureter

The sigmoid colon and sigmoid mesocolon, the left colic vessels, and the left ovarian vessels.

Posteriorly:

Right ureter

The right psoas muscle and the bifurcation of the right common iliac artery.

Left ureter

the left psoas muscle and the bifurcation of the left common iliac artery.

The inferior mesenteric vein lies along the medial side of the left ureter.

(B) Pelvic part

The ureter crosses over the pelvic inlet in front of the bifurcation of the common iliac artery. It runs downward and backward in front of internal iliac artery and behind the ovary until it reaches the region of the ischial spine. It then turns forward and medially beneath the base of broad ligament, where it is crossed by the uterine artery. The ureter then runs forward lateral to the lateral fornix of the vagina , to enter the bladder.

Blood supply Arteries Upper end the renal artery. Middle portion testicular or ovarian artery. In the pelvis superior vesical artery.

Veins Venous blood drains into veins that correspond to the artery.

Lymph drainage

The lymph drains to the lateral aortic nodes and the iliac nodes.

Nerve supply

Renal , ovarian, and hypogastric plexuses.

Urinary Bladder

Urinary Bladder

Urinary bladder is a muscular reservior of urine, which lies in the anterior part of the pelvic cavity. The bladder varies in its size, shape and position according to the amount of urine it contains.

(A) An empty bladder is tetrahedral in shape and has:

1- an apex, directed forwards.

2- a base or fundus, directed backwards

3- a neck, the lowest and most fixed part of the bladder.

4- three surfaces, a superior and two inferolateral.

5- four borders, two lateral, an anterior and a posterior.

(B) A full bladder is ovoid in shape and has:

1- an apex, directed upwards towards the umbilicus.

2- a neck, directed downwards

3- two surfaces, anterior and posterior.

Relations 1- Apex is connected to umbilicus by the median umbilical ligament which represents the obliterated embryonic urachus.

2- Base is related to the uterine cervix and vagina.

3- Neck is the lowest and most fixed part of the bladder. It lies (3-4)cm behind the lower part of pubic symphysis and pierced by the internal urethral orifice. It is related to pelvic fascia which surrounds the upper part of urethra.

4- superior surface: peritoneum covers the greater part of the superior surface, except for a small area near the posterior border, which is related to the supravaginal part of the utrine cervix. The peritoneum is reflected to the isthmus of uterus to form the vesicouterine pouch.

5- inferolateral surfaces are devoid of peritoneum,

and are seprated from each other anteriorly by the anterior border, and from the superior surface by the lateral borders. Each surface is related to pubis, pubovesical ligaments, retropubic fat, levator ani and obturator internus.

The mucous membrane of the greater part of the empty bladder is thrown into folds that disapper when the bladder is full. The area of mucous membrane covering the internal surface of the base of the bladder is referred to as the trigone. Here, the mucous membrane is always smooth, even when the viscus is empty.

The superior angles of the trigone correspond to the openings of the ureters, and the inferior angle to the internal urethral orifice. The trigone is limited above by a muscular ridge, which runs from the opening of one ureter to that of the other and is known as the interureteric ridge.

The muscular coat of the bladder is composed of smooth muscle and is arranged as three layers of interlacing bundles known as the detrusor muscle.

At the neck of the bladder, the circular component of the muscle coat is thickened to form the sphincter vesicae. The ureters pierce the bladder wall obliquely, and this provides a valvelike action, which prevents a reverse flow of urine toward the kidneys as the bladder fills.

Ligaments of bladder (A) True ligaments

These are condensation of the pelvic fascia around the neck and base of the bladder, which are continuous with the fascia on the superior surface of levator ani.

1- Lateral true ligament of the bladder

2- Lateral pubovesical ligament

3- Medial pubovesical ligament

4- Median umbilical ligament

5- Posterior ligament of the bladder

(B) False ligaments These are peritoneal folds, which do not form any

support to the bladder. They include: 1- median umbilical fold 2- medial umbilical fold 3- lateral false ligament 4- posterior false ligament

Blood supply Arteries

The superior and inferior vesical arteries, branches of the internal iliac arteries, supply the bladder.

Veins

the veins form the vesical venous plexus, which drained into the internal iliac vein.

Lymph drainage

The lymph vessels drain into the internal and external iliac nodes.

Nerve supply The nerve supply to the bladder is from the inferior hypogastric plexuses. The sympathetic fibers originate in the first and second lumber ganglia and descend to the bladder via the hypogastric plexuses.

The parasymthetic fibers arise as the pelvic splanchnic nerves from the second, third, and forth sacral nerves; they pass through the inferior hypogastric plexuses to reach the bladder wall.

Most afferent sensory fibers arising in the bladder reach the central nervous system via the pelvic splanchnic nerves, some afferent fibers travel with the sympathetic nerves via the hypogastric plexuses and enter the first and second lumber segments of the spinal cord.

The sympathetic nerves inhibit contraction of the detrusor muscle of the bladder wall and stimulate closure of the sphincter vesicae. The parasympathetic nerves stimulate contraction of the detrusor muscle of the bladder wall and inhibit the action of the sphincter vesicae.

Female urethra

1- female urethra is only 4cm long and 6mm in diameter. 2- it begins at the internal urethral orifice at the neck of the bladder, roughly 5cm behind the middle of the pubic symphysis. It runs downwards and forwards embedded in the anterior wall of the vagina, traverses urogenital diaphragm, and ends at the external urethral orifice in the vestibule of vagina.

3- Near the bladder neck, the urethra is lined by transitional epithelium. The rest of the urethra is lined by stratified squamous epithelium. 4- Female urethra is easily dilatable and the catheters or cystoscopes can be easily passed.

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